1. Field of the Invention
The present invention relates to a slewing ring brake for use in heavy machinery including earthworking machinery. More particularly, the present invention relates to a brake for a slewing ring.
2. Description of Related Art
The use of a slewing ring in heavy machinery such as earthworking machinery is well known. In an excavator, for example, there is generally provided a fixed lower chassis and a rotatable upper chassis mounted in a rotary manner to the lower chassis. A circular track or a slewing ring having a tooth system on its outer circumference is generally fixedly attached to the lower chassis. The upper chassis generally includes gears which may be engaged with the tooth system and be rotationally actuated in order to allow rotation of the upper chassis with respect to the fixed lower chassis. This rotation may be actuated by a drive such as hydraulic motors. Thus, in order to rotate the upper chassis with respect to the lower chassis, it is only necessary for the drive to overcome the frictional torque and the moment of inertia of the mass. Therefore, it is relatively easy to rotate the upper chassis in this manner.
However, this relatively easily attained rotation of the upper chassis can cause serious problems in use of these heavy machineries such as earthworking machinery. For instance, if the upper chassis includes a fixed rotary drill for making a hole in the ground, a relatively high torque can act on the upper chassis during the drilling process. This high torque caused by drilling can cause an undesired rotation of the upper chassis with respect to the lower chassis. Of course, this can cause serious problems in safety and can significantly impair the accuracy of the drilled hole.